Simultaneous ultrasonic experiment of dynamic and static elastic parameters of coal under formation pressure conditions in Qinshui Basin

The static elastic parameters play a very important role in reservoir fracturing, and prediction of fracture and stress field. In order to obtain the relationship between dynamic and static elastic parameters, the dynamic and elastic parameters were tested under formation pressure conditions, which supply rock physics basis for transforming dynamic parameters into static parameters. Using MTS (a rock mechanics test system) we measure simultaneously the dynamic and static elastic parameters of coal samples in HS region of Qinshui Basin under formation pressure conditions in this study. Experimental results show that: dynamic Young's modulus increases with pressure, while dynamic Poisson's ratio varies relatively complicated with pressure; dynamic and static Young's modulus show a good liner relation, and dynamic Young's modulus is higher than static Young's modulus; dynamic and static Poisson's ratio have poor correlation, and dynamic Poisson's ratio is lower than static Poisson's ratio for most coal samples. These relations provide basic data for transforming dynamic parameters into static parameters, providing a new method for forecasting static elastic parameters and obtaining mechanical property of coal rock using seismic data.